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Tryptoline structure.png
CAS number 16502-01-5 N
PubChem 107838
ChemSpider 96979 YesY
Jmol-3D images Image 1
Molecular formula C11H12N2
Molar mass 172.226 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Tryptoline, also known as tetrahydro-β-carboline and tetrahydronorharmane, is a natural organic derivative of beta-carboline. It is an alkaloid chemically related to tryptamines. Derivatives of tryptoline have a variety of pharmacological properties and are known collectively as tryptolines.


Many tryptolines are competitive selective inhibitors of the enzyme monoamine oxidase type A (MAO-A). 5-Hydroxytryptoline and 5-methoxytryptoline (pinoline) are the most active monoamine oxidase inhibitors (MAOIs) with IC50s of 0.5 μM and 1.5 μM respectively, using 5-hydroxytryptamine (serotonin) as substrate.

Tryptolines are also potent reuptake inhibitors of serotonin and epinephrine, with a significantly greater selectivity for serotonin. Comparison of the inhibition kinetics of tetrahydro-β-carbolines for serotonin and epinephrine reuptake to that of the platelet aggregation response to these amines has shown that 5-hydroxymethtryptoline, methtryptoline, and tryptoline are poor inhibitors of reuptake. In all respects 5-hydroxytryptoline and 5-methoxytryptoline showed greater pharmacological activity than the tryptoline and methtryptoline.

Although the in vivo formation of tryptolines has been a matter of controversy, they have profound pharmacological activity.

There is evidence that tryptolines may be potent neurotoxins that may play a role in Parkinson's Disease[1]

See also[edit]